Nippon Steel Corporation

Harima Ceramic Co. Ltd.

Krosaki Corporation

Harima Refractory Co., Ltd.

Toshihiro Isobe

Osami Matsumoto

Teruyuki Nishitani

Shigeru Fujiwara

Hideo Yaoi

Yasuhisa Abe

Yukihiro Suekawa

Satoshi Nagai

Masayosi Nagahara

Takashi Genba

Hisashi Matsuoka

Syouichi Itose

A refractory of the invention is used in casting operation, which has good spalling resistance and corrosion resistance. The refractory includes: 0.0357-2.6548 wt % of amorphous silica particles having a specific surface area within a range of 15-30 m.sup.2 /g; 8.8495-28.5612 wt % of alumina particles having a particle diameter within a range of 10-50 mm; 1.3986-18.1715 wt % of at least one of fused magnesia and sintered magnesia, which contains 0.6993-10.9041 wt % of magnesia having a maximum particle diameter under 44 .mu.m; 0.6993-13.630 wt % of alumina cement; and 45.4545-88.1417 wt % of alumina. When the refractory is used, at lease one of fused magnesia and sintered magnesia surrounds the alumina particles, which react together to generate spinel to thereby form micro-crack layer around the alumina particles for preventing propagation of cracks in a refractory structure.

Refractory for use in casting operations

Basic monolithic refractories of which the chemical composition consists essentially of, in oxide equivalence, 65%-96% by weight of MgO, 2.6%-20% by weight of ZrO.sub.2, 1.3-10% by weight of SiO.sub.2, 2% or less by weight of CaO, 0.5% or less by weight of Fe.sub.2 O.sub.3 and 1% or less by weight of Al.sub.2 O.sub.3, and with a mineral composition containing periclase as the main component and cubic zirconia and forsterite as sub-components, and with apparent porosity of 7% or less and bulk density of 3.2 g/cm.sup.3 or more. Basic monolithic refractories under this invention possess excellent slaking resistance, slag erosion resistance, slag penetration resistance and spalling resistance. They exhibit an excellent service life, especially as lining material for steel-making furnaces.

Basic monolithic refractories

A refractory for casting a basic substance comprises 100 parts by weight of a refractory aggregate having as main ingredients 3 to 40% by weight of zircon and 97 to 60% by weight of magnesia and a suitable amount of a binding agent. Another refractory for casting a basic substance comprises 100 parts by weight of a refractory aggregate having as main ingredients 3 to 40% by weight of zircon and 97 to 60% by weight of magnesia, not more than 7 parts by weight of metallic fibers, and a suitable amount of a binding agent. The refractories for casting a basic substance are used for ladles, tundishes, vacuum degasing furnaces, mixers, and the like.

Refractory for casting a basic substance

An alumina-spinel monolithic refractory consists essentially of 50-90 percent by weight of alumina clinker, 5-40 percent by weight of MgO--Al.sub.2 O.sub.3 spinel clinker not larger than 1 mm in size and 1-25 percent by weight of alumina cement. Another alumina-spinel monolithic refractory consists essentially of 50-90 percent by weight of alumina clinker, 5-40 percent by weight of MgO--Al.sub.2 O.sub.3 spinel clinker, 1-25 percent by weight of alumina cement and not more than 5 percent by weight of magnesia clinker. The alumina-spinel monolithic refractories are used for lining the inner walls of ladles, vacuum degassing vessels, hot-metal mixers, blast-furnace troughs and their covers, not-metal mixer cars, tundishes and the like.

Alumina-spinal monolithic refractories

A non-fired silicon-carbide base refractory mixture comprising 95 to 99.5% (in respect to the mixture) of silicon carbide containing 1.5 to 8% (in respect to the silicon carbide) of particles not larger than 1.mu. and 0.5 to 5% of super-fine silica powder containing at least 50% of particles not larger than 1.mu. after a coagulation.

Non-fired silicon carbide refractories

Growing community of inventors

Hyogo, Japan

Toshihiro Isobe